Study Shows Massive Magma Chamber Lies Beneath Vesuvius

Mount Vesuvius, the volcano most famous for blanketing the towns of Pompei and Herculaneum with lava and debris in A.D. 79, may be sitting atop a reservoir of magma that covers more than 400 square kilometers, a new study suggests. The finding, reported in the current issue of the journal Science by a group of Italian and French scientists, may lead to more accurate monitoring of the area surrounding the volcano.

Building on previous work that suggested the presence of a magma zone underneath Vesuvius, Emmanuel Auger of the Universit¿ di Napoli Federico II in Naples, Italy, and colleagues employed seismic tomography to estimate its size. The scientists produced seismic waves and traced their paths through the zone beneath Vesuvius. Using the speed and direction of the waves, they compiled an image of the crust under the volcano. The picture that emerged, the researchers report, includes a magma reservoir buried eight kilometers deep in the earth's crust that is at least 400 square kilometers wide. "This also tells us that there is a huge amount of available magma under Vesuvius," co-author Paolo Gasparini says. "It was really unexpected for the reservoir to be that size, so very wide and large."

A better understanding of the reservoir's structure, location and volume, the authors write, "can be used to help prediction of the scenario of the next eruption and to interpret the pattern of the expected precursory seismic activity and ground deformation." Unfortunately for the region's inhabitants, however, it can't help predict when the next eruption will occur.